Runtime inspection utilities for Python typing module





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Typing Inspect

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The typing_inspect module defines experimental API for runtime inspection of types defined in the Python standard typing module. Works with typing version 3.7.4 and later. Example usage:

from typing import Generic, TypeVar, Iterable, Mapping, Union
from typing_inspect import is_generic_type

T = TypeVar('T')

class MyCollection(Generic[T]):
    content: T

assert is_generic_type(Mapping)
assert is_generic_type(Iterable[int])
assert is_generic_type(MyCollection[T])

assert not is_generic_type(int)
assert not is_generic_type(Union[int, T])

Note: The API is still experimental, if you have ideas/suggestions please open an issue on tracker. Currently typing_inspect only supports latest version of typing. This limitation may be lifted if such requests will appear frequently.

Currently provided functions (see functions docstrings for examples of usage):

  • is_generic_type(tp): Test if tp is a generic type. This includes Generic itself, but excludes special typing constructs such as Union, Tuple, Callable, ClassVar.
  • is_callable_type(tp): Test tp is a generic callable type, including subclasses excluding non-generic types and callables.
  • is_tuple_type(tp): Test if tp is a generic tuple type, including subclasses excluding non-generic classes.
  • is_union_type(tp): Test if tp is a union type.
  • is_optional_type(tp): Test if tp is an optional type (either type(None) or a direct union to it such as in Optional[int]). Nesting and TypeVars are not unfolded/inspected in this process.
  • is_literal_type(tp): Test if tp is a literal type.
  • is_final_type(tp): Test if tp is a final type.
  • is_typevar(tp): Test if tp represents a type variable.
  • is_new_type(tp): Test if tp represents a distinct type.
  • is_classvar(tp): Test if tp represents a class variable.
  • get_origin(tp): Get the unsubscripted version of tp. Supports generic types, Union, Callable, and Tuple. Returns None for unsupported types.
  • get_last_origin(tp): Get the last base of (multiply) subscripted type tp. Supports generic types, Union, Callable, and Tuple. Returns None for unsupported types.
  • get_parameters(tp): Return type parameters of a parameterizable type tp as a tuple in lexicographic order. Parameterizable types are generic types, unions, tuple types and callable types.
  • get_args(tp, evaluate=False): Get type arguments of tp with all substitutions performed. For unions, basic simplifications used by Union constructor are performed. If evaluate is False (default), report result as nested tuple, this matches the internal representation of types. If evaluate is True, then all type parameters are applied (this could be time and memory expensive).
  • get_last_args(tp): Get last arguments of (multiply) subscripted type tp. Parameters for Callable are flattened.
  • get_generic_type(obj): Get the generic type of obj if possible, or its runtime class otherwise.
  • get_generic_bases(tp): Get generic base types of tp or empty tuple if not possible.
  • typed_dict_keys(td): Get TypedDict keys and their types, or None if td is not a typed dict.

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